GSoC'14: KNN on SP-GiST

Greetings, Postgres community!

I'm a student of the Moscow Institute of Physics and High Technology and am
writing to you scince I'm willing to join the community starting with
participation in this GSoC at your side by carrying out the project
"Support KNN for SP-GiST".

Unfortunately, I hadn't have the ability to manage it out at least couple
of days before, so all the project discusscion will happen after the
application deadline. But technically the main skeleton of the project is
ready and commited in form of the proposal (named "Support KNN for
SP-GiST"). Nevertheless, as melange states, it's still editable in case of
need and can be improved as the discussion flows onward. So, what's your
opinion about it, are there any corner stones that need to be detailed
right away? From the first sight it feels straightforward enough, but your
comments will be of great use scince I'm totally new to Postgres and
probably miss out of my sight many significant particularities.

Thanks in advance, Vlad Sterzhanov \ quadrocube